1. Field of the Invention
The present invention relates to a method of firing magnetic cores, and more particularly, to a method of firing flattened-ring magnetic cores included in noise-suppressing components and other such apparatuses, as well as, a method of firing thin magnetic cores included in noise filters, inductors of transformers, and other such apparatuses.
2. Description of the Related Art
A flattened-ring magnetic core 21 shown in FIG. 5 is known for use as a core in a noise-suppressing component. A signal line such as a flat cable is inserted into a flattened through-hole 22 of the magnetic core 21, and high-frequency noise propagating through the signal line is eliminated. Typically, a cross section of the magnetic core 21 has a length L of a longer side of 10 mm to 100 mm and a length T of a shorter side of 1 to 10 mm, and the through-hole 22 has a length t of a short side of 0.3 mm to 8 mm. The magnetic core 21 is assembled and fired by providing a plurality of flattened-ring compact bodies, which are made of a ferrite material and are provided with the flattened through-holes 22, at an opening surface thereof in a firing container (not shown in the drawing) so that the axes of the through-holes 22 are vertically oriented, and then firing the compact bodies 21 in this arrangement.
A thin magnetic core 210 shown in FIG. 10 is known for use in a noise filter, an inductor of a transformer, and other such components. The core 210 is assembled and fired by arranging a plurality of thin compact bodies 210 made of a ferrite material vertically at one side thereof in a firing container (not shown in the drawing), and firing the compact bodies in this arrangement.
At this stage, each of the flattened-ring compact bodies 21 or the thin compact bodies 210 is spaced apart so that adjacent flattened-ring compact bodies 21 or adjacent thin compact bodies 210 do not stick together during firing. If the adjacent flattened-ring compact bodies 21 or the adjacent thin compact bodies 210 stick together, a chemical reaction may occur in the compact bodies when connected together or contacting each other, or breaks or cracks may occur when the connected compact bodies 21 or 210 are detached from each other by applying mechanical force.
With respect to the conventional method of firing magnetic cores, it is relatively easy to arrange the compact bodies 21 or 210 in a perpendicular orientation in a firing container in which they are placed with sufficient space when the compact bodies 21 or 210 are large, and in particular, when the compact bodies 210 are thick. In such a case, even if slight vibrations and shocks are applied, the flattened-ring compact bodies 21 or the thin compact bodies 210 are not inclined, and the adjacent flattened-ring compact bodies 21 or the adjacent thin compact bodies 210 do not easily stick together during firing.
However, recently, as magnetic cores become thinner and smaller, it is often necessary to fire small flattened-ring compact bodies 21 or small thin compact bodies 210 while they are vertically oriented and spaced apart from each other. In such a case, it is difficult to vertically position separately each of the small flattened-ring compact bodies 21 or the small thin compact bodies 210. When the compact bodies 21 or 210 are small, slight vibrations easily cause the compact bodies 21 or 210 to be tilted, and the adjacent flattened-ring compact bodies 21 or thin compact bodies 210 are brought into contact with each other, and thus a chemical reaction may occur therebetween, or adherence, breaks, or cracks which are not visibly detectable may occur, resulting in an increase in the defect rate, or a decline in reliability of the product.
In order to overcome the problems described above, preferred embodiments of the present invention provide a method of firing magnetic cores in which firing is performed with a high degree of reliability and mass production is enabled.
According to one preferred embodiment of the present invention, a method of firing magnetic cores includes the steps of attaching a powder to the surface of a plurality of flattened-ring compact bodies made of a magnetic material and having flattened through holes, arranging the plurality of flattened-ring compact bodies adjacently so that the axes of the flattened through-holes of the flattened-ring compact bodies are vertically oriented, and firing the flattened-ring compact bodies while the powder is interposed between the adjacent flattened-ring compact bodies. The powder may preferably include an inorganic material or an organic material having particles with a particle size of about 1,000 xcexcm or less.
In another preferred embodiment of the present invention, a method of firing magnetic cores includes the steps of attaching a powder to the surface of a plurality of thin compact bodies made of a magnetic material, vertically arranging the plurality of thin compact bodies adjacently, and firing the thin compact bodies while the powder is interposed between the adjacent thin compact bodies. The powder may preferably include an inorganic material or an organic material having particles with a particle size of about 1,000 xcexcm or less.
The powder attached to the surface of the compact bodies functions as a spacer between the adjacent compact bodies. Therefore, the compact bodies can be arranged in the container by stacking them together, thus facilitating the setting operation. When the compact bodies are fired, the adjacent compact bodies are not brought into direct contact with each other, and thus inconveniences such as reactions in the contact surface therebetween, adherence, and breaks do not occur.
Other features, elements, advantages, steps and characteristics of the present invention will be described in more detail below with reference to the attached drawings.